Hob grinder



C. G. OLSON aon enmnmx Fi led Feb. 5. 192s 3 Sheets-Sheet 1 [/v VEN TOR w m A w G W c April 24, 1928. 1,667,488

c. a, oLs oN HOB GRINDER Filed Feb. 5. 1926 a Sheets-Sheet 2 .[NVENTOR CARL. G.- OLSON /irrrls.

April 24, 1928. 1,667,488

' C. G. OLSON HOB GRINDER Filed Feb. 5. 1926 s Sheets-Sheet s Patented Apr. 24,1928- I UNITED STATES- CARL G. OLSON;

. 1,667,488 PATENT OFFICE] or CHICAGO, ILLINOIS, ASSIGNOR 'ro ILLINOIS TOOL wonxs, or

' CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

non GRINDER.

' Application filed February 5, 1926. Serial No. 86,206.

My invention relates to hob grinding'ma chines and the object of the invention is to.

are arranged in the form of a helix, the mat-' ter of changing the grinder from one side of the teethto the opposite side involves adjustment which is somewhat complex. In the case of straight gashed hobs still another factor must be taken into consideration, due to the fact that the body of the tooth is not at right angles to the gash. My purpose is to provide means whereby .the necessary changes and adjustments may be taken care ofin a. simple and reliable manner.

I accomplish my object by the mechanism illustrated in the=accompanying drawings.

Figure 1 is an assembly view of the principal parts concerned with my invention. Some of the parts are shown in vertical axial section in order tobetter reveal the construction. 1

Figure 2 is a rear elevation of parts of the machine shown in Figure 1. This view shows the grinder head and parts immediately supportingit and in dotted lines indicates an alternate position which the grinder head may occupy for grinding a hob of the opposite lead or handK In other words this ,figure illustrates the change from a right to a left hand hob.

Figure 3 is a plan view of the grinder head and its support. This figure also shows'the hobend a portion of the liob spindle.

Figure 4 is a sectional elevation on the line 44 Figure 3. 4o

Figure 5 1s a sectional elevation on the line 5-5 Fig. 4.

Figure 6 is a perspective view of the grinder head, adjusting shim, tool rest and anchor bolt, the parts being separated. to

show their construction and to indicate their relationship in the assembled maehine.

Figure) 7 is diagrammatic view illustrat-- ing the reasons for changing the elevation of the grinder in changing from one side ofthe hob teeth to the other-when treating a straight gash hob. This adjustment may for convenience be termed the vertical shift.

Figure 8 is also diagrammatic and shows on a larger scale the reasons for making 85 theWertical shift or adjustm'ent.

Figure 9 is a detail view partially diagrammatic showing the relation ofthe.

grinding wheel to the hob in the dilferent positions.

Like numerals denote like parts throughout the several views.

The hob 1 is. supported upon the hob spindle 2. 'In Figures 1, 3 and 4 a spiral gash hob is illustrated while in the diagram'Figures 7 and 8 a straight gashed hob is illustrated. The hob spindle has a rotary movement about its own axis and'also a longitnv dinal or axial movement lengthwise of its axis and also a radial movement for moving the hob bodily toward and from the grinding wheel in conformity with the relief of the hob teeth. These movements may be accomplished in difi'erent ways without exceeding the scope of my invention. In the illustrated case the mechanism for producing these movements of the hob is like the one shown in my earlier-Patent No. 1,57 5,- 713. It will besufficient for the present purpose'to say that the hob spindle is journaled in two bearings 41, 7 mounted in a frame 6 which is in the form of a housing closed by a cover 8.- The journal 6 is internally threaded andconstitutes a lead nut in which works the threaded end portion 10 0f the hob lief in the hob teeth. One part 12 of the support is shown in Figure 1 and a steel tape 14 is inserted between the housing and lts'support for holding the housing in position as explained in my aforesaid patent.

The hob spindle isrotated by a gear which'is fastened to it and meshes with wit face-driving pinion 18. This is driven by suitable gearing including apinion '20. The

pitch circle of pinion 18 is tangent to the plane of the support 1 2.

is controlled by a feed screw 26. A cross :carriage28 is slidingly mounted on the carriage 22 and is controlled by an adjusting? sci'ew 30. A tool'rest or base 32 is supporte on carriage 28. It pivots about a pin 34 and has arcuate slots .36 for receiving clamping Now referring to the'grinder and its support: A tool carriage 22 slides upon a guide 24 arranged crosswise of the hob spindle. It

. after described.

screws 38by which the tool rest may be held in the proper angular adjustment. This determines the angle of obliquity between the hob spindle and the grinder spindle herein- Above the tool rest is a grinder head and this comprises a block shaped shank 40-and a sleeve 42 which forms. an extension or dle axis are arranged at an angle to the hob bracket from it, and holds a quill 44. The spindle 46, which supports the grinder wheel 48, is journaled in the quill and driven by a sheave 50 and belt 52. For clearance and other reasons the sleeve 42 and grinder spinspindle axis when the shank block is at right angles to it as shown in Figure 3. In the form shown the top and bottom surfaces of the shank block; 40 are parallel.

sleeve and is held in adjusted position by a set screw 54.

The shank 40 rests' ordinarily upon a wedge block 56 shown separately in perspective in Figure 6.. This block rests upon thetop of the tool rest 32 and has a central aperture 58 for accommodatingan anchor bolt 60 by which the parts may be clamped together. w'At the lower end the anchor bolt or clamping screw 60 is suitably fastened to the support 32 by means of a pin 62 as best shown in Figures 4 and 5. The shank 40 is centrally apertured to accommodate the bolt and is held down by a nut 64 screwing on the up er end of the bolt The wedge b for engaging locating pins 68 projecting upward from the. tool rest 32. These pins prevent the wedge block from shifting in any direction upon the surface of the tool rest.

Channels 70 are formed in the upper and lower surfaces of the shank and these -fit over the rounded upperends of the locating pins.

, grinder head may change its angular position upon the top of the tool rest in accordance with the shape of the wedge block but will beheld by the pins against shifting in a direction transverse to channels 70. These channels extend transversely to the hob spindle and permit the grinder to be adjusted radially toward and from the hob.

M In -practice,'the parts are assembledas' shown in Figures 1 to 5 inclusive.- It will be observed that the axis of the conical grinding wheel lies at an oblique-angle to a vertical .plane passing through -,the hob axis and also to a horizontal plane .passing ing the parts areso adjusted that the median: line of the'shank of the grinder head will' pass through the centerrof thespace between through the hob axis. With a given shaped grinding 'wheel the first angle varies in accordance with the pressure angle of the teeth and the second angle varieswith' the helix angle of the hob. In preparing for rindlock has a slot 66 at. each end The construction is snch that the.

the two lines of contact of the grinder on the hob teeth. In other-words; when the grinder acts upon a tooth and when acting uponbe necessary to make an adjustment of either the hob or the grind'in wheel in a direction lengthwise of the ho This principle is illustrated diagrammatically in Figure 9 wherein M represents the. median line. It is the same as the upper portion of the line .44 in Figure 3. The quill is slidable longitudinally in a When one side of the-hob teeth have'been ground the grinder head isliftedoif and turned over so that it will be reversed from the position shown in full lines in Figure 9 to the position shown in dotted lines in said figure. This is accomplished 'by first removing the nut 64 from the anchor bolt 60, then lifting oil the grinder head and turning it over and then securing the'parts in the new position by reapplying the nut- 64. In the case of the smaller single thread hobs this reversing of the grinder head is made Withcout disturbing the wedge' block and while this imparts a slight discrepancy theroreti- 'cally the inaccuracy is so small as a practical matter that it is negligible. In the case of hobs of larger sizes or larger helix angles and in hobs of double thread another factor must be taken into consideration. This will be understood by reference to the diagrams,

-Fi ures 7 and 8', whichshow a straight gash ho An adjustment must be made which will cause the grinder to commence its work at thefront of the hob tooth when the grinder is reversed. In the diagram the line F F represents the front of the teeth facing any given gash. "The line A-A represents a normal to the line-of contact whenthe grinder i's'on one side of the space, andthe line B B represents a normal tothe line of contact when the rinder is on the other side of the space. I we assume that the line F-Fliesin a horizontal lane it is evident that if the grinder is at rst locatedat the elevation indicated by the center of the full line circle .it must; when reversed; be low cred-to the extent indicated by the'center of the dotted line circle C. For the sake of.

explanation this lowering may bereferre'd 'to as the vertical shiftfalthough it will'be :understood that the term vertical is .em- I ployed becaus'e'in the illustrated embodiment of the invention the shift would be vertical.

To express the principle universally it would be more accurateto say that there is a relative adJustment represented by a narrow angle centered atthe hob axis and lying in a plandperpendicular to the axis of the hob. In my machine this vertical shift is accomplished in a-very simple and effective manner, and that is bysubstituting a thinnerv Wedge block when the grinder head is reversed. By employing this expedient the grinder head will automatically" come both to the correct angles and to. the correct elevation and will cause the grinder to make the necessary horizontal shift (lengthwise of-the hob) without requiring any other manipulation of the machine on the part of the operator. Thus in my machine, in

' spindle, a grinder spindle, a base frame,

means 'for causing relative movement between, the base .frame and the hob spindle in a direction parallel to the hob spindle, a

grinder spindle frame fog holding the grinder spindle at an oblique angle to the hob axis, and removable means insertible between the base frame and the grinder spindle frame for holding the latter at an angle with thehob spindle corresponding with the helix angle of the hob.

2. A hob grinder having a hob spindle, a grinder spindle, a base frame, means for causing relative movement between the base.

frame and the hob spindle in a direction parallel to the liob spindle, a grinder head for holding the grinder spindle, said grinder head being reversible, top for bottom, and separate means cooperating with the grinder head and base frame for supporting the grinder head in either of two positions for grinding opposite sides of the hob teeth and automatically compensating for the helix angle of the hob and the axial spacing of the surfaces to be ground. v

3. A hob grinder having a hob spindle, a grinder head, a support for the grinderhead, and a removable plate insertible between the support and with the grinder head for holding the grinder head at'a specific angle, depending upon the shape of the detachable element.

4. Ahob grinder having a hob spindle, a grinder head, a support for the grinder head,

tween the support and the grinder head -whereby the grinder head may be held at different angles by substitutingplates of and a removable wedge plate located be-.

glilinder head provided with a block shapeds ank, a tool rest, and means on the tool rest and located beneath the shank block for holding the latter and the grinder spindle at the proper angle to correspond with the helical lead of the hob, the shank block having parallel top and bottom surfaces.

'6.'A hob rinder having a hob spindle, a grinder head provided with a block shaped shank whose top and bottom surfaces are parallel, a tool rest, and an angular block inserted between the shank block and the tool rest for holding the grinder spindle in proper position with .respectto the helix angle of the hob.

7. A hob grinder having a hob spindle, a

grinder head provided with a block shaped.

shank whose top and bottom surfaces are parallel, a serted between the block shaped shank and tool rest, an angular block in the tool restfor bringing the grinder into I proper cont'actual relation with the hob teeth in accordance with the helix angle :of the hob, and screw clamp mechanism for clamping the block shaped shank to the tool rest at the angle determined by the shape of the angular block.

8. A hob grinder having a hob spindle. a grinder spindle, means for causing relative travel of said spindles in a direction parallel to the axis of the hob, a. grinder head reversible top for bottom for'holding the grinder spindle in predetermined position relatively to the hob spindle axis in accordance with the slope of the sides of the hob teeth, and compensating means for holding the grinder head in either of two positions, 1

' said com ensating means holding the grinder at di erent levels when in different positions to thereby maintain symmetrical grinding contacts on opposite sides of the hob teeth.

9. A hob grinder having a hob spindle, a grinder head having a block shaped shank having parallel top and bottom surfaces. a toolrest, a removable block on which the shank of the grinder head sea-ts, said block seating upon the tool rest, and locating keys rigidl held in one of the parts and fittinginto t ie other part for positioning the shank of the grinder head on the tool rest. said keys passing through holding the latter in position also.

the removable block for i 10. A hob grinding machine having a hob spindle, a grinder-head, a support for the grinder -head, and removable substitute blocks of different thicknesses to holdthe grinder head at' different elevations for grinding on different sides of the hob teeth. 11. A hob grinder having a hob spindle, a grinder head, means for causing relative movement between the hobspindle and grinder head for relieving the work, a grinding wheel rotatably mounted in .the grinder head with the axis at an oblique angle to a grinder head, means for causing relativev the axis of the hob, and substitute spacer the wheel is in contact with different sides of the hob teeth.

12. A hob grinder having a hob spindle,

movement between the-hob spindle and the grinder head for relieving the work, a grinding wheel rotatably mounted in the grinder head With't-he axis at an oblique angle to the axis of the hob in conformlty with the pressure angle of the hob, and supporting means for the grinder head capable of delin itely holding the grinder head in two positions one hundred and eighty degrees apart for grinding opposite sides of the hob teeth and adapted to automatically maintain the same level at the point of .contact of the grinder wheel with the hob when the grinder head is changed from one position to am other.

a grinder head, means for causing relative movement between the hob spindle and the grinder head for relieving the work, a

'grinding wheel rotatably mounted in the grinder head with its axis at an oblique angle to-the axis of. the hob in conformity with the pressure angle of the hob, and supwork, said base holding the grinder head porting means for the grinder head capable of holding the grinder head in two pos tions one-upside down with respect to the other for grinding opposite sides of the hobteeth and adapted to automatically'adjust the grinder head-both in a direction parallel to the axis of thework and in a direction .-perpendicu lar to a plane containing the axis -of the work and the point of a plication of the grinder to the work when e grinder head is'changed from one position to another.

14., A'hob grinder having a'hob spindle,

a grinder head, means fol-causing relative movement between the hob spindle and the grinder head for relieving the work, a gr1nding' wheel rotatably mounted in the grinder head with its axis at-an oblique axis angle...

to the axis; of the-hob in conformity' w1th the (pressure angle of the hob, the grinder hea having parallel-top and bottom surfaees, a

13. A hob grinder having a hob spindle,

having a reversible block-shaped'shank support for said shank, and interfitting means between the support and the shank, the interfitting portion on the block'being in such-position that when the shank is reversed, top' for bottom, the grinder wheel will be adjusted axially of the hobv to 'contact the opposite side of the hob tooth.-

15. A hob grinding machine having a grinder head which may be reversed by being' turned over, said grinder head when.

support therefor, and two wedge blocks of different thickness for insertion between them in difl'erent positions of the grinder head, whereby when the grinder head is merely turned over and the alternate block positioned, the grinder will be at changed elevation, and the grinder will make line contact with the tooth on the opposite-side 'of the space-and the grinder spindle axis will he at the corresponding pressure and helix angles.

16. In a machine for grinding hobs and like threaded objects, a work spindle, a.

grinder head, and a base on which the grinder head is supported, the grinder head being reversible top for bottom, wherebiy the grinder may be turned over for' grin ing the opposite sides of the thread of the tilted at anangle corresponding to the helix angleof the thread of the work.

17. In a machine for grinding hobs and like threaded objects, a work spindle, a grinder head,- and a base on which the grinder head is supported, the grinder head being reversible top for bottom, whereby the grinder may be turned over for grinding opposite sides of the thread of the work, said base holding the grinder head tilted at an angle corresponding -to the helix angle of the thread of the work, the base' being In witness whereof, I have hereunto subscribed my name CARL G. oLsonf 

